Toothbrush

ABSTRACT

A toothbrush comprising a head, a neck and a handle, the head comprising a readily flexed resilient member having a plurality of bristles arranged on one side thereof, and a rigid member depending from the neck, the resilient member resting on the rigid member and being arranged with an inner array of bristles between outer arrays of bristles on opposite sides thereof, the outer arrays being caused to splay divergingly from the resilient member as a consequence of deformation of the resilient member when the bristles are urged onto a tooth or gum surface.

This invention relates to toothbrushes. In particular, it relates toflexible toothbrush heads which allow the bristles to optimise theircleaning configuration in use, and to methods of cleaning teeth usingsuch special toothbrush heads.

Toothbrushes have been known since time immemorial. However, there hasbeen a constant search for toothbrushes which seek either to improve thecomfort and ease of brushing, or to improve the efficiency of brushing,by modifications to the bristles, brush head or handle.

It is known to mount the bristles of a toothbrush on a resilient head,and support that head from the brush handle in such a way that theresilient head deforms in use, thereby altering the bristle orientation.For example, in WO 94/13174, there is described a toothbrush havingbristle tufts mounted on a readily flexed resilient member, which isprelerably in the form of an elongated sheet. In use, when the centralportion of the brush is pushed against the occlusal surfaces of theuser's teeth, with the resilient member deforming from its normallybowed position, thereby bringing into engagement with the teeth and gumsthe outer bristles on the head.

This brushing action is only part of the repertoire normally observed inusers, and under more general and random brushing action splayedbristles, as distinct from bunched bristles, are recognised as providinghigh degrees of crevice intrusion, and therefore a high level ofcleaning efficiency.

We have found that by suitably mounting onto a rigid member a flexibleresilient member on which bristle tufts are mounted, it is possible toconfigure the brush head such that the bristles indine or splay in usein a controlled manner, thereby providing optimal cleaning.

Thus, according to its broadest aspect, there is provided a toothbrushcomprising a head, a neck and a handle, the head comprising a readilyflexed resilient member having a plurality of bristles arranged on oneside thereof, and a rigid member depending from the neck, the resilientmember resting on the rigid member and being arranged with an innerarray of bristles between outer arrays of bristles on opposite sidesthereof, the outer arrays being caused to splay divergingly from theresilient member as a consequence of deformation of the resilient memberwhen the bristles are urged onto a tooth or gum surface.

According to a further aspect, there is provided a toothbrush comprisinga head, a neck and a handle, the head comprising a readily flexedresilient member with a plurality of bristles mounted on one sidethereof, and a rigid member depending from the neck, the rigid memberhaving an upper surface on which the resilient member rests and acentral longitudinal axis, the bristles on the resilient member beingarranged with an inner array of bristles between outer arrays ofbristles on opposite sides thereof, the readily flexed resilient memberbeing mounted along the central longitudinal axis of the rigid member,the resilient member being free to deform adjacent the centrallongitudinal axis of the rigid member.

In such an embodiment, when for example the brush is not in use, theresilient member adjacent the central longitudinal axis of the rigidmember, which may support the outer arrays of bristles, may not bedirectly supported by the rigid member. As a result, in use it may befree to deform, causing the effects described herein.

Conveniently, both the inner and outer arrays of bristles may compriseone or more longitudinal rows of closely spaced adjacent bristle tufts.

The resultant deformation of the resilient member adjacent the centrallongitudinal axis of the rigid member may cause the outer arrays ofbristles to incline relative to the inner array, in a direction whichdiverges from the inner array.

In certain embodiments, the readily flexed resilient member may besupported on the rigid member along the whole length of the centrallongitudinal axis of the rigid member. In a preferred embodiment, theresilient member may be mounted on but not attached to the centrallongitudinal axis of the rigid member, but additionally mounted on andactually attached to the brush head by attachment to one or more lateralextensions of the rigid member, which may extend perpendicular to thecentral longitudinal axis. Such lateral extensions of the rigid membermay be for example at one or both ends of the brush head, or in themiddle of the brush head.

The brush according to the invention is designed so that in use at leastsome of the outer bristles of the-bristle array may be caused to splayoutwards when the inner array of bristles are brought into contact withteeth and gums. In the context of the invention, the "inner array" ofbristles may conveniently be one or more (for example two) longitudinalrows of bristle tufts. This effect may be caused by the configuration ofthe brush head; when the inner array of bristles are brought intocontact with the teeth or gums of the user, the resilient member onwhich they are mounted is supported and held in place by the centrallongitudinal axis of the rigid member, which does not allow theresilient member immediately underneath the inner bristles to deform.

In contrast, the resilient member underneath the outer bristle array isnot similarly constrained, and it is free to deform as a result ofpressure applied to the end of the bristles remote from the resilientmember. As a result of this deformation, the resilient member may becaused to deform for example to an arc or angled shape, with the innerbristles remaining in their original position, but the outer bristlesbeing forced downwards with regard to their original position. Thisdownward movement of the outer bristles may also cause them to splaywith regard to their original orientation, thereby pointing in adiverging manner relative to their original configuration. This isthought to provide the benefit of improved crevice intrusion of thebristles, in particular the outer bristles in the bristle array, betweenthe user's teeth, thereby improving cleaning efficiency.

In preferred embodiments of the invention, the central longitudinal axisof the brush may comprise an elevated surface, such as a ridge, whichmay be edged or flat surfaced, and which runs longitudinally along thebrush head, and is located on the upper surface of the rigid member,contacting in use the under side of the resilient member.

Preferably, the bristles of the toothbrush are anchored to the readilyflexible resilient member in a series of tufts, and extend from theresilient member in parallel to each other, and in a directionperpendicular to the surface of the resilient member, when the brush isnot in use. The bristles may be manufactured from any material used inthe art to make toothbrush bristles; preferred materials include nylon6.12, or polybutyl terephthalate.

The resilient material on which the bristles are mounted canconveniently be any natural or synthetic elastomeric material, includingfor example low or high density polyethylene, tetrafluore ethylene,polyurethane, polypropylene, or synthetic rubber. The bristle tufts canbe mounted on or in the resilient member by suitable manner, such asinjection moulding techniques, or by mounting the bristles mechanically,adhesively, or by fusion onto or into the resilient member.

The invention will now be described by way of example only, in which;

FIG. 1 shows a perspective exploded schematic view of a configuration oftoothbrush head according to the invention;

FIG. 2 shows a schematic cross sectional view of a toothbrush headaccording to the invention;

FIG. 3 shows a schematic cross section view of the brush head of FIG. 2in use;

FIG. 4 shows a schematic exploded perspective view of a furtherembodiment of toothbrush head according to the invention; and

FIG. 5 shows a schematic exploded perspective view of another embodimentof toothbrush head according to the invention.

Referring to FIG. 1, there is shown the head of a toothbrush, with thehandle omitted. The head comprises a rigid member comprising a solidbase portion 1, having attached thereto at one end a neck portion 2, forattachment to a brush handle (not shown). Base portion 1 and neck 2 havebeen integrally moulded from a rigid material, preferably a rigidplastics material, such as polypropylene, though they could as easily bemanufactured from styrene acrylonitrile copolymer. Base portion 1 haslongitudinal parallel sides, and a "gables end" shape in cross section,the top of the gables being a ridge 3, on which the resilient materialsupporting the bristles rests. Ridge 3 in this embodiment represents thecentral longitudinal axis of the brush, running longitudinally andcentrally along the brush head, and also being located on the uppersurface of the rigid base portion adjacent the under side of theresilient member.

Base portion 1 is shaped so as to have two end portions 4a, 4b, whichare essentially rectangular in transverse cross section. The brush headincluding end portions is typically 28 mm long and 13 mm wide, and endportions 4a, 4b are typically 13 mm wide, 6 mm high, and 3 mm deep.

A plurality of schematically represented bristle tufts, 5, are supportedon a resilient material base 6, made of polypropylene. The bristles areconfigured with an inner array 7 which comprises a longitudinal straightrow of adjacent bristle tufts, having an either side an outer array, 8a,8b, which comprises a longitudinal straight row of adjacent bristletufts. The resilient material 6 may be attached to end portions 4a, 4bof the brush head, for example by plastic rivets 9a, 9b, 9c, 9d whichpenetrate the resilient materials through holes 10a, 10b (not shown),10c, 10d, in resilient material 6, and lock into cooperating holes onbase portion 1.

In use, as the user manipulates the brush head in the mouth, the innerarray of bristles 7 will have a cleaning action on the teeth, butbecause of the action of ridge portion 3 on the underside of theresilient material 6, the inner array of bristles 7 are maintained, atleast at a position on or close to ridge 3, in a direction which issubstantially perpendicular to the plane of the brush head, and in theiroriginal orientation. However, the resilient material portion of thebrush which supports the outer array of bristles 8a, 8b, is at least inpart not directly supported by the rigid base portion 1, and as a resultis free to deform in use under a pressure applied to the tops of theouter arrays of bristles 8a, 8b. As a result, the deformed configurationof the resilient material causes the bristles to have a splayedconfiguration. However, the rigid sloping sides of base portion 1 limitthe deformation of the resilient material 6 possible, and thereby act torestrict the degree of splaying of the bristle configuration.

This configuration may confer benefits to the brush in terms of itsability to penetrate crevices in the mouth.

It is highly preferred that the material which constitutes the resilientmember is in fact more resilient, and more deformable than the materialfrom which the bristles are manufactured, in order to maximise thereadiness of the resilient material to deform in use, and therefore theability of the brush bristles to splay.

FIG. 2 shows a transverse cross section of a brush similar to that shownin FIG. 1, except that the end portions of the base portion are notshown. The rigid member base portion 21 of this embodiment likewise hasa gables end cross section, with a plurality of bristle tufts 25attached to a resilient member 26, which rests on ridge 23. In thisembodiment, the inner array of bristles 27 comprises two longitudinalstraight rows of adjacent bristles tufts, whilst the outer array 28comprises a single longitudinal straight row of bristle tufts on eachside of the inner array 27.

FIG. 3 shows the brush of FIG. 2 in use, being pressed up against atooth surface 300. As can be seen, in use the resilient member 36 isunable to deform near its centre where it is held in place by ridge 33resting on base portion 31. As a result, the inner array of bristles 37are retained at essentially the same angle and orientation relative tothe base portion 31. However, the outer arrays 38, not being soconstrained by the rigid base portion 31 below the resilient member, arefree to incline and splay relative to the inner array 37.

FIG. 4 shows an alternative configuration of toothbrush head accordingto the invention.

In this embodiment, the toothbrush head likewise has a rigid base member41, and two end portions 44a, 44b. Brush neck 42 is attached to endportion 44b. Resilient member 46 has attached to it a plurality ofbristle tufts 45; in this embodiment the inner array 47 comprise twolongitudinal straight rows of adjacent bristle tufts, whilst the outerarray 48 comprises a longitudinal straight row of adjacent bristle tuftson each side of the inner array 47. Resilient member 46 may convenientlybe attached to rigid base member 41 by a series of pegs (not shown),which can conveniently pass through holes 410a, 410b (not shown) 410c,410d, and lock into corresponding holes on the rigid base member 41which extend perpendicularly from flattened edge 43 (incorporating thecentral longitudinal axis of the brush head), by conventional means.

The bristles 47 of this embodiment are in the form of a sculptured trim,where the bristles are not of the same length. In this embodiment theinner array of bristles 47 is shorter than the outer array 48, andadditionally the ends of the bristles are shaped so as to have a "V"configuration when viewed from one end of the brush head. Other bristletrims are generally envisaged as different embodiments of the invention,such as for example a ripple trim.

FIG. 5 represents a further and preferred configuration of toothbrushaccording to the invention.

In this embodiment, the rigid base member 51 has a "sharp edge" ridgeportion 53, on which the underside of resilient member 56 rests. Brushneck 52 is attached to the end of rigid base member 51. Resilient member56 may additionally rest on, and be anchored to, end portions 54a, 54band in addition raised cross member 54c, which is located laterallyacross the middle of the brush head, and extends perpendicularly to thecentral longitudinal axis of the brush head, which runs along ridge 53.Conveniently this may be done by pegs or studs, which may pass throughholes 510e, 510f, 510g (not shown) and 510h (not shown) in resilientmember 56, and lock into cooperating holes in end portions 54a, 54b andcross member 54c, by conventional means.

Resilient member 56 has attached to its upper side bristle tufts 55(shown schematically), which comprise an inner array 57 of twolongitudinal straight rows of adjacent bristle tufts, and an outer array58 which comprises a longitudinal straight row of adjacent bristle tuftson each side of the inner array 57. In this embodiment the bristles ofinner array 57 are shorter than those of the outer array, the bristlesin each array being of uniform length with each other.

In use, the resilient member may be constrained by the end portions 54a,54b, cross member 54c and ridge 53, but may be free otherwise to deform,with the four corners of the array in particular being capable ofdeforming and therefore causing inclination of the bristles mounted onthese parts of the resilient member, as previously described.

A preferred feature of this embodiment, which may be equally applied toother embodiments, is the elastomeric skirt 511, which depends from theresilient member 56 in a direction opposite that in which the bristlespoint, and conveniently covers the sides of the rigid base member 51.The elastomeric skirt can conveniently be attached to the periphery ofrigid member 51, for example by ultrasonic welding thereto.Alternatively, the elastomeric skirt may be attached to a back platewhich runs under the rigid member 51 on the side opposite the brush headbristles, and attached thereto by for example ultrasonic welding, orgluing. Skirt 511 has molded into it access hole 512, which provides thetoothbrush neck 52 access to the rigid base member 51. The elastomericskirt 511 can confer advantages to the brush head in terms of hygiene,gum massaging capabilities and also its comfort to the user in use.

As the skilled person will appreciate, many variations on the inventionare possible without departing from the spirit of the invention. Forexample, the brush head may be any convenient shape, such as for exampletriangular, diamond shaped or arrow head shaped, in addition torectangular. In addition whilst the schematic representations have oftenbeen drawn as being highly angular, the corners on brush embodiments, inparticular on the rigid member, may be rounded for extra comfort.

What is claimed is:
 1. A toothbrush comprising a head, a neck and a handle, the head comprising a readily flexed resilient member with a plurality of bristles mounted on one side thereof, and a rigid member depending from the neck and having at least one lateral extension attached to the resilient member, the rigid member having an upper surface on which the resilient member rests and a central longitudinal axis including an elevated surface running longitudinally along at least a portion of the brushhead located adjacent the resilient member, the bristles on the resilient member being arranged with an inner array of bristles between outer arrays of bristles on opposite sides thereof, the readily flexed resilient member being mounted along the central longitudinal axis of the rigid member, the resilient member being free to deform adjacent the central longitudinal axis of the rigid member.
 2. A brushhead according to claim 1 wherein the resilient member further comprises an elastomeric skirt flanking the head and covering sides of the rigid member. 